U.S. patent application number 11/379728 was filed with the patent office on 2006-10-26 for direct current combiner box with power monitoring, ground fault detection and communications interface.
Invention is credited to Ronald Bradley McClintock, Leif Ronnie Pettersson.
Application Number | 20060237058 11/379728 |
Document ID | / |
Family ID | 37185601 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060237058 |
Kind Code |
A1 |
McClintock; Ronald Bradley ;
et al. |
October 26, 2006 |
Direct current combiner box with power monitoring, ground fault
detection and communications interface
Abstract
A combiner box is used to collect direct current from solar
panels or other energy sources. The combiner box integrates all
means necessary for ground fault detection, current monitoring,
voltage monitoring, and power monitoring. The combiner box may
include a communication interface suitable for Web enabled
monitoring, electronic notifications of system status, and/or
remote control of system functions. In one embodiment, the combiner
box uses integrated circuits and printed circuit board technology
to achieve new efficiencies in manufacturing, installation and
system analysis at the string level. A separate hand piece may be
used by installers to test the performance of the combiner box,
installation of the solar panels, performance of the solar panels
and connections between the solar panels and the combiner box.
Inventors: |
McClintock; Ronald Bradley;
(Novato, CA) ; Pettersson; Leif Ronnie; (Novato,
CA) |
Correspondence
Address: |
STEVEN A. NIELSEN;ALLMAN & NIELSEN, P.C
100 Larkspur Landing Circle
Suite 212
LARKSPUR
CA
94939
US
|
Family ID: |
37185601 |
Appl. No.: |
11/379728 |
Filed: |
April 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60673991 |
Apr 25, 2005 |
|
|
|
Current U.S.
Class: |
136/244 |
Current CPC
Class: |
Y04S 10/123 20130101;
Y02E 40/70 20130101; H02J 13/0003 20130101; Y02E 40/72 20130101;
H02J 7/35 20130101 |
Class at
Publication: |
136/244 |
International
Class: |
H02N 6/00 20060101
H02N006/00 |
Claims
1. An apparatus for combining and monitoring each string of
entering direct current comprising: means for detecting current in
one or more strings of entering direct current; and means of
combining direct current entering the apparatus.
2. The apparatus of claim 1 with means of monitoring power in one
or more strings of direct current.
3. The apparatus of claim 1 with means of communicating system
status.
4. The apparatus of claim 1 with means to perform remote
diagnostics upon the apparatus.
5. The apparatus of claim 1 with means to detect ground faults by
comparisons of the positive and negative components of each
entering string of direct current.
6. The apparatus of claim 5 with means of using computer software
to analyze the positive and negative components of each entering
string of direct current.
7. The apparatus of claim 1 using one or more integrated circuits
to analyze each string of direct current entering the
apparatus.
8. The apparatus of claim 7 with means to discontinue input from
any string that has reached a ground fault state.
9. The apparatus of claim 1 wherein a direct current measurement is
converted into a proportional voltage value.
10. The apparatus of claim 9 wherein the proportional voltage value
is converted into a proportional digital value.
11. The apparatus of claim 10 wherein the analog to digital
conversion occurs for each entering string of direct current.
12. The apparatus of claim 11 using integrated printed circuit
board components.
13. The apparatus of claim 12 wherein the digital signals may be
remotely monitored.
14. The apparatus of claim 13 wherein system functions may be
remotely controlled.
15. The apparatus of claim 1 with means to accept a separate
communication apparatus.
16. The apparatus of claim 15 wherein the attached communication
apparatus has means of communicating system status.
17. The apparatus of claim 1 with means to accept a separate data
processing unit.
18. The apparatus of claim 1 with means to accept a separate
testing apparatus.
19. A method of combining and monitoring strings of direct current
entering a single apparatus comprising the steps of: attaching to
the apparatus a positive and a negative component from each string
of direct current; using integrated circuits to measure the current
from each string; and using a positive bus and a negative bus to
collect power from each string of direct current.
20. The method of claim 19 wherein the direct current measurement
is converted into a proportional voltage measurement which is in
turn converted into a proportional digital value.
21. The method of claim 20 wherein a hand piece is attached to the
apparatus to test the installation and performance of the
apparatus.
22. The method of claim 20 wherein a data processing unit is
attached to the apparatus.
23. The method of claim 22 wherein a communication component is
used to transmit information regarding each string of direct
current.
24. The method of claim 23 wherein the communication component may
be used to remotely control the system.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of the filing of U.S.
Provisional Patent Application Ser. No. 60/673,991 entitled "Direct
Current Combiner Box with Power Monitoring, Ground Fault Detection,
and Communications Interface", filed on Apr. 25, 2005, and the
specification and all parts thereof are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to the use and construction of
combiner boxes suitable for collection of direct current generated
by photovoltaic cell panels (solar panels) and other energy
sources. The present invention allows for ground fault detection,
remote monitoring and control of system status at a system level
and/or for each string of direct current entering the combiner box.
Optional data processing circuitry may be installed within the
disclosed combiner box and an optional hand piece may be used to
check system status and installation.
DESCRIPTION OF THE RELATED ART
[0003] U.S. Pat. No. 6,930,868 by Kondo (the '868 patent) discloses
a solar power generation method where ground fault detection occurs
after strings of DC power are aggregated. Ground fault detection
occurs at the DC/AC inverter where an AC leakage component is
calculated. One string of DC current in a ground fault state will
stop all power generation at the DC/AC inverter. The '868 patent
fails to provide system analysis or ground fault detection for any
particular string of solar panels entering the power collection
system. The '868 patent discloses an inefficient method of ground
fault detection as one string of solar panels in a ground fault
state will "tie up" the entire system and waste the power generated
by the remaining strings of solar panels. The '868 patent does not
provide means to quickly ascertain which string is in a ground
fault state.
[0004] U.S. Pat. No. 6,713,890 by Kondo (the '890 patent) discloses
a power generator that disconnects power at a point after the DC/AC
inverter. A moving part disconnects in the event of a ground fault.
Disconnection status requires a visual inspection of each DC/AC
inverter ground fault switch and physical manipulation to reset the
system. As separate DC/AC inverters and disconnection switches are
used for each DC input, no consolidation of components is
possible.
[0005] The '890 patent relies upon complex analysis of AC leakage
current and current filters. The '890 patent fails to disclose
means of measuring DC current directly and requires separate DC/AC
inverters and physical switches for each DC power input or string
of solar panels.
[0006] U.S. Pat. No. 6,624,350 by Nixon, (the '350 patent)
discloses a solar power management system that checks for polarity
at each input of DC power and provides visual indications of
polarity. The '350 patent does not provide means of monitoring
ground fault status for each input of DC power, thus, a ground
fault from one DC power input halts the entire system.
SUMMARY OF THE INVENTION
[0007] The present invention overcomes shortfalls in the related
art by providing a new combiner box to economically and efficiently
monitor and isolate individual strings or circuits of DC power.
Each string of DC power has a negative component attached to the
negative bus of the combiner box and a positive component attached
to the positive bus of the combiner box. At or near either bus,
integrated circuitry is used to monitor and report current, current
differential and power for each entering string or circuit of DC
power. Integrated circuitry may, if necessary, shut off individual
strings of DC input, allowing the other inputs to continue power
production through the combiner box.
[0008] The present invention overcomes shortfalls in the '868
patent by analyzing current differentials directly and in proximity
to the positive and negative bus, before current reaches an
inverter. Thus, the present invention does not require the use of
extra hardware to factor out current leakage from a DC/AC inverter.
The present invention consolidates ground fault detection and other
needed functions by use of a single combiner box that accommodates,
controls and reports on individual strings of DC current.
[0009] The present invention overcomes shortfalls in the '890
patent by controlling input to the combiner box at the string
level. In the present invention, if one string is in a ground fault
state, the remaining strings still contribute power to the combiner
box and energy generation continues. The '890 patent discloses a
switch the shuts down all power to an inverter in the event of a
ground fault.
[0010] The present invention overcomes shortfalls in the '350
patent by providing ground fault detection and ground fault
interruption at the string level. Any ground fault occurring in the
system disclosed in the '350 patent shuts down the entire
system.
[0011] The disclosed combiner box allows for continuous monitoring
of system performance so that problems such as poor connections or
sub-standard photovoltaic cell panels may be detected and repaired
before causing a ground fault or decreases in current. The
disclosed invention monitors and reports gradual or sudden changes
in current, so that repairs may be made to keep power and income
generation maximized. By monitoring and controlling direct current
circuits at the string level, significant time is saved by pin
pointing poorly performing strings.
[0012] In large commercial applications multiple photovoltaic cell
panels may be connected in series to compose a string that is
attached to the combiner box. Each string or circuit is attached to
the negative and positive bus in parallel. The use of integrated
circuits within the combiner box removes the need for expensive and
bulky transducers at each string.
[0013] The artful design of the disclosed combiner box adds direct
current monitoring capability in a compact form that saves time in
installation. The prior art required a separate control unit to be
wired to and through the combiner box. Such wiring added
complexity, expense and the potential for errors in the
installation of solar power systems.
[0014] The use of a printed circuit board allows for flush mounting
into the combiner box. An installer merely places the connections
from the solar panels into either side of the combiner box. All
monitoring circuitry in integrated into the printed circuit
board.
[0015] An optional hand piece may be inserted into the disclosed
combiner box by the installer to check current, current
differential, power and other information for each string. The
ability of the combiner box to accept a diagnostic hand piece
allows for quick, in the field analysis of system performance. An
installer may quickly pin point installation problems at the string
level. The ability to accept a diagnostic hand piece allows for the
use of combiner boxes without the optional "head unit" described
below.
[0016] An optional controller or "head unit" may be installed
within the disclosed combiner box to allow for local or remote
reporting of diagnostic analysis and system information. The
optional controller includes means of transmitting system status
over the Internet using standard protocols and means for remotely
monitoring and controlling overall system functions and individual
strings or circuits. Users may receive system information and
remotely control system functions by various means including cell
phones, PDAs, or computers with Internet access.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] FIG. 1 is a schematic diagram of the combiner box.
[0018] FIG. 2 is a schematic diagram of the combiner box with the
optional communications module.
[0019] FIG. 3 is a block diagram of numerous combiner boxes
powering one inverter.
DETAILED DESCRIPTION
[0020] The following detailed description is directed to certain
specific embodiments of the invention. However, the invention can
be embodied in a multitude of different ways as defined and covered
by the claims. In this description, reference is made to the
drawings wherein like parts are designated with like numerals
throughout.
[0021] Unless otherwise noted in this specification or in the
claims, all of the terms used in the specification and the claims
will have the meanings normally ascribed to these terms by workers
in the art.
[0022] 100 of FIG. 1 shows the disclosed combiner box with three
input DC circuits, however, additional or fewer circuits may be
disposed within the combiner box. 600 is the perimeter of the
combiner box.
[0023] 400 is the positive connection point for a DC power source
such as a solar cell. Along the same circuit is a bank of fuses
103, bank of DC current sensors 104, bank of controlled switches
105, and the positive bus 101 at connection point 401.
[0024] The negative connection point for the first input DC circuit
or string starts at 402 passes through DC current sensor block 106
and connects to the negative bus 102 at connection point 403.
[0025] The second string of positive DC input may enter at 404. The
second string of negative DC input may enter at 406. The third
string of positive DC input may enter at 405. The third string of
negative DC input may enter at 407. Additional strings of DC input
may be added to the combiner box.
[0026] An inverter or other load may be connected to the positive
output 501 and negative output at 502.
[0027] Integrated control circuit blocks 104 and 106 measure string
currents and convert the currents into proportional voltages.
[0028] Analog to digital converter 200 receives voltages from the
104 block of integrated control circuits. Analog to digital
converter 203 receives voltages from the 106 block of integrated
control circuits. Analog to digital converter 201 receives a
voltage potential from the negative bus 102 and positive bus 101.
Analog to digital converters 200, 201 and 203 accept voltages and
convert the voltages into proportional digital values. The
proportional digital values from converters 200, 201 and 203 enter
the data processing unit 301.
[0029] Data processing unit 301 monitors total current for each
string, current differential for each string, voltage, and system
status. Data processing unit 301 has means to utilize computer
software and means to provide input to control circuit 300. Control
circuit 300 has means to control all switches in the 105 block.
Each switch in the 105 block is controlled on an individual basis
allowing for example ground fault interruption on a string by
string basis.
[0030] In an alternative embodiment A/D converters 200, 201, 203,
control circuit unit 300, and data processing unit 301 are not
originally supplied with the combiner box 100, but may be installed
subsequently as an upgrade as an optional "head unit".
[0031] In this alternative embodiment, the combiner box 100 may
accept an optional diagnostic hand piece that reports system
status, status for each string and other data useful for testing
system performance and diagnosis of possible installation
problems.
[0032] FIG. 2 shows the disclosed combiner box 100 with the
optional communications module 700 which sends and receives
information to and from the data processing unit 301. The
communications module 700 has means to transmit and receive signals
through standard network protocols. Communications module 700
allows remote users to monitor system performance and control
system functions. Remote users may access the system through PDA's,
cell phones, the Internet, or other methods.
[0033] FIG. 3 shows a possible combination of solar panels and
combiner boxes configured to supply power to a DC/AC inverter 904
or other load. Solar panels 900 are connected in series to solar
panels 901. Together, solar panels 900 and 901 are connected as one
string or circuit of DC input to combiner box 902.
[0034] Solar panels 907 and 908 are connected in series and
together are connected as one string or circuit of DC input to
combiner box 902.
[0035] The output of combiner box 902 is connected as a string or
circuit of DC input to combiner box 903 which supplies power to the
DC/AC inverter 904.
[0036] Solar panels 905, 909, and 910 are connected to combiner box
906 as separate strings of DC input. The output of combiner box 906
enters combiner box 903 as a string or circuit of DC input.
Combiner box 903 supplies power to the DC/AC inverter 904.
* * * * *